This application is based on Japanese Patent Application 2002-228943 filed Aug. 6, 2002 and Japanese Patent Application 2002-234988 filed Aug. 12, 2002, the disclosures of which are incorporated herein by reference in their entireties.
1. Field of the Invention
The present invention relates to support devices in which a gas chamber that supports an object using gas is supported on a support frame, the manufacturing method thereof, stage devices that incorporate such support devices, and to exposure apparatus that include such stage devices and that are used in manufacturing, for example, semiconductor integrated circuits and liquid crystal displays.
2. Description of Related Art
Conventionally, in lithography processes, which are processes used in manufacturing semiconductor devices, a variety of different exposure apparatus have been used to transfer onto a substrate, such as a wafer or glass plate coated with resist (a photosensitive material), circuit patterns fabricated on masks or reticles (hereinafter termed xe2x80x9creticlesxe2x80x9d).
For example, reduction projection exposure apparatus, which use projection optical systems to reduce and transfer onto wafers patterns from reticles, have been used as the primary exposure apparatus for semiconductor devices, given the miniaturization of the minimum line widths of the patterns (the device scale) accompanying the increased levels of integration in integrated circuits in recent years.
Step-and-repeat type stationary exposure reduction projection exposure apparatus (so-called xe2x80x9csteppersxe2x80x9d), in which the reticle pattern is transferred sequentially to multiple shot regions (exposure regions) on a wafer, and step-and-scan type scanning exposure apparatus (so-called xe2x80x9cscanning steppersxe2x80x9d), in which, as an improvement to the steppers, the reticle pattern is transferred to each shot region on the wafer as the reticle and the wafer synchronously move in one dimension, as disclosed in Japanese Patent Publication Laid-Open No. 8-166043, are known as types of reduction projection exposure apparatus.
In these types of reduction projection exposure apparatus, often the stage device includes a main column, which supports the reticle stage, the wafer stage, the projection optical system (the projection lens), and the like, that is mounted on an anti-vibration platform to eliminate floor vibrations, and which is mounted on a base plate, which is provided as a foundation that is first placed on the floor. In recent years, the stage devices have included active anti-vibration platforms, in which air mounts having a controllable internal pressure, and actuators such as voice coil motors (devices that provide a linear force) have been provided and mounted on the main column (the main frame), and the forces of the aforementioned voice coil motors, etc., are controlled based on measurement values from, for example, six accelerometers.
FIG. 15 shows one example of a support device with an air mount. The support device shown in this figure is one in which an air mount 81, as an air spring, is supported on a support frame 82. The air mount 81 is equipped with a pressure sensor 84, which senses the pressure in an internal space 83, where air at a specific pressure is released or filled through a servo valve 85 based on the detection results of the pressure sensor 84. The air mount 81 is equipped with a piston 87, which is supported by a diaphragm 86 in such a way that it can move freely, and, using the air of the internal space 83, the piston 87 supports the object to be supported 88, such as the projection lens or the stage. Thus, by interposing the air mount 81 as an air spring between the object 88 and the support frame 82, the vibrations propagated to the projection lens, the stage, or the like, from the support frame 82 through the object 88 are controlled.
In addition, an anti-vibration device equipped with a voice coil motor in an air mount is disclosed in Japanese Patent Publication Laid-Open No. 5-340444.
However, the conventional technologies described above have problems such as described below. When it comes to vibration control, the lower the stiffness of the air spring, the better. However, because the stiffness of the air spring and the volume of the air spring are inversely proportional, a large volume is required in order to obtain a low-stiffness air spring. Given this, although one may consider increasing the volume of the internal space in the air mount or consider attaching an air tank to the air mount, in either case it would directly cause the equipment to be larger, and it would be difficult to secure the large volume, given footprint constraints (i.e., constraints on the floor space for installation).
In particular, recent years have seen steadily increasing demands for further miniaturization in semiconductor devices and for faster exposure processes, and although a variety of methods have been investigated by which to prevent the vibrations from the floor in the factories in which the exposure equipment is installed, and the vibrations accompanying the movement of the stage within the exposure equipment, from reaching the projection lens, the constraints on the space within the exposure equipment limit the volume of the air spring, so there is a danger that it will become impossible to satisfy the increasingly strict anti-vibration performance requirements for future exposure apparatus.
Furthermore, given only the description in Japanese Patent Publication Laid-Open No. 5-340444, it is not possible to apply the anti-vibration device disclosed in Japanese Patent Publication Laid-Open No. 5-340444 to high-precision equipment such as exposure apparatus.
The present invention was created in consideration of the above, and one of its objects is to provide a support device that functions as a low-stiffness air spring, without increasing the size of the equipment, and to provide a manufacturing method of the support device, as well as provide a stage device incorporating the support device, and an exposure apparatus having the stage device.
In order to achieve the objects described above, as well as other objects, the present invention provides various features.
A support device according to one aspect of the present invention includes a first gas chamber that is filled with a gas at a specified pressure and that supports an object using the gas, and a support frame that supports the first gas chamber, wherein a second gas chamber, connected to the first gas chamber, also is provided within the support frame.
In the support device according to this aspect of the present invention, the volume of the air spring will be the volume of the second gas chamber and the volume of the first gas chamber, making it possible to reduce the stiffness of the air spring. Furthermore, because the second gas chamber is provided within the support frame, it is possible to prevent increases in the size of the equipment, such as would occur when the volume of the first gas chamber is increased or when an air tank is added to the first gas chamber.
In addition, the stage device may include a stage unit that moves on a platform, wherein the platform is supported by the support device. In such a stage device, the low-stiffness air spring makes it possible to support changes in the load on the platform caused by moving the stage unit, and makes it possible to prevent the propagation of floor vibrations to the platform.
According to another aspect of the present invention, an exposure apparatus includes a projection optical system to expose a pattern of a mask that is supported on a mask stage, onto a photosensitive substrate that is supported on a substrate stage, wherein at least one of the mask stage, the projection optical system, and the substrate stage is supported by a support device according to any of the various aspects of the invention. In the exposure apparatus according to aspects of the present invention, the low-stiffness air spring makes it possible to support changes in the load on the platform caused by moving the mask stage or the substrate stage, and makes it possible to prevent the propagation of floor vibrations to the platform or to the projection optical system.
Another aspect of the invention relates to a manufacturing method for a support device that is provided with a first gas chamber which is filled with a gas at a specified pressure and that supports an object using the gas, and a support frame that supports the first gas chamber, comprising: a step of forming a casting mold of the support frame by providing a first core within the mold that has a hollow part, and by providing a second core that is in contact with the first core and the mold; a step of injecting molten material into the mold; and a step of, after the material that has been injected has cooled, removing the mold, the first core, and the second core, to form a second gas chamber, which can connect to the first gas chamber.
In the manufacturing method for the support device according to this aspect of the present invention, it is possible to form a second gas chamber, which forms an air spring volume, in addition to the volume of the first gas chamber, within the support frame, thus making it possible to reduce the stiffness of the air spring. This second gas chamber is provided within the support frame, and thus is able to prevent the size of the equipment from increasing, as would be the case if the volume of the first gas chamber were increased, or if an air tank were added to the first gas chamber.
A support device according to another aspect of the present invention has a support surface that supports an object, a gas chamber that is filled with gas to a specified pressure and that uses the gas to support the object, in a first direction that is perpendicular to the support surface, a drive device that is disposed in the gas chamber and that uses an electromagnetic force to drive the object in the first direction, and a temperature adjustment device that adjusts the temperature of the drive device. In the support device according to this aspect of the present invention, an increase in size of the equipment can be prevented by disposing the drive device within the gas chamber. Furthermore, the direction in which the object is supported by the gas chamber, and the direction in which the object is driven by the drive device, can be coaxial, making it possible to prevent deformation, or the like, of the object because no torque will be applied to the object. In addition, because the temperature adjustment device adjusts the temperature of the drive device, the object will not be affected by the heat produced by the driving of the drive device.
The stage device may include a stage unit that moves on a platform, wherein the platform is supported by the support device. In the stage device according to this aspect of the present invention, variations in the load on the platform due to movements of the stage unit can be supported by the drive device and by the gas chamber, and even the elimination of the floor vibrations can be done without increasing the size of the equipment, while, additionally, it is possible to prevent any deformation, etc., of the object because no torque is applied to the platform. Furthermore, the stage unit is unaffected by heat generated by driving of the drive device.
An exposure apparatus according to another aspect of the present invention is an exposure apparatus in which a pattern of a mask held by a mask stage is exposed by a projection optical system onto a photosensitive substrate held on a substrate stage, wherein at least one of the mask stage, the projection optical system, and the substrate stage, is supported by the support device. In the exposure apparatus according to this aspect of the present invention, even if the mask stage or the substrate stage is moved, deformations, or the like, can be prevented because no torque is applied to the mask stage, the substrate stage, or the projection optical system. In addition, the mask stage and the substrate stage are not affected by heat generated by driving the drive device. Because of this, it is possible to prevent the reduction of the exposure accuracy without increasing the size of the equipment, and thus it is possible to handle miniaturization of devices with ease.